Field
The present disclosure relates to a display device, an information processing apparatus, a method for controlling a display device, and a storage medium.
Description of the Related Art
Users of information processing apparatuses such as smartphones, tablet personal computers (PCs), and personal digital assistants (PDAs) have been increasing recently. Information processing apparatuses incorporating a touch panel as an input device are becoming common.
For example, a touch panel incorporated in an information processing apparatus is mounted on a display device such as a liquid crystal display (LCD). If the user makes a predetermined touch operation via the touch panel, a request for an operation of the information processing apparatus is accepted.
For example, the user makes touch operations to implement functions such as scrolling of a display area with respect to a display image displayed on the LCD and scaling of the display area.
Among touch panels, there is a typical type of a touch panel using a panel configured so that two opposed layers of resistive films inside are electrically connected to each other at a pressed point (hereinafter, referred to as a resistive film type touch panel).
To calculate the pressed point of the touch panel, a constant voltage is applied to one electrode of the upper resistive film. The other electrode is grounded. A voltage value at the pressed point is detected via the lower resistive film to calculate a coordinate value in an X-axis (Y-axis) direction.
On the foregoing resistive film type touch panel, desired coordinate values can be calculated if the user touches a single point of the touch panel.
If the user simultaneously touches a plurality of points on the touch panel, one average point of the touched positions is calculated. For example, if the user's palm accidentally touches the touch panel while the user is making a touch operation with a fingertip, the coordinate values of the position touched with the fingertip are unable to be calculated.
To prevent erroneous input due to the touching of a plurality of points on the resistive film type touch panel, a technique has been discussed for disabling touch operations if touches are detected at a plurality of points (see Japanese Patent Application Laid-Open No. 2000-250710).
Such control disables touch operations without exception, even if the user unintentionally touches a plurality of points. Since touch operations are disabled while the user is making an intended operation, the user can mistakenly think that the apparatus is broken.
What is needed is a mechanism that, if a user operates a touch panel, can notify the user of a factor of change into a state in which a touch operation is not accepted to restore a state in which a normal touch operation is accepted.